In English this is lexically determined: redden, whiten, blacken;
green, yellow, purple (no suffix); but blue and brown cannot form
causative forms at all. Stative verbs do not exist.
But in German, the Christmas song "O Tannenbaum" has the line
"Du gruenst im Winter", which seems to mean that you (the fir tree)
are green, not that you become green.

> imagine what they would be:
> *rouger = to be red
> *bleuer = to be blue
> *verder = to be green

It's interesting that whereas the causatives are -ir verbs, you
automatically put these statives into the -er conjugation (which perhaps
is explained because it is the only conjugation still accepting new
verbs).

This is a most classical exposition of the notorious francophone
desire to have a distinct word for everything, noted by many IAL
designers and enthusiasts.
--
My corporate data's a mess! John Cowan
It's all semi-structured, no less. http://www.ccil.org/~cowan
But I'll be carefree jcowan@reutershealth.com
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On an XML DBMS.